Input systems for inputting handwritten or hand-drawn graphical information into a computer are widely used together with different types of graphics software, for example CAD programs or web design programs. These input systems include a drawing device, and also a base or support for the latter. The drawing device can consist of an electronic pen which is intended to be held in a user's hand and is moved in desired pen movements across the base for inputting graphical information, such as handwriting, drawings, geometric figures, graphical patterns, symbols, numbers or the like. WO 01/71473 describes the use of such an electronic pen.
In this connection it is desirable to increase the user's possibilities of acting on the appearance of the graphical information produced or on other properties associated with the graphical information. Thus, in many applications it is necessary, or at least expedient, for the user to be able to specify purely graphical properties such as line thickness, line color, and the choice between solid, broken or dotted lines. The selectable properties for the graphical information can also be of a more advanced character, for example properties which allow the graphical information to look as if it has been produced by a special pen, such as a calligraphy pen, or by means of an airbrush technique. The selectable properties can also concern whether certain graphical information is intended to be visible or invisible or can simply indicate that particular information is intended to be read only by a certain recipient or group of recipients.
There are traditional ballpoint pens with which it is possible to write with ink in different colors. Such multicolor pens comprise a set of buttons which are arranged on the pen and are used to select the desired color. It would be obvious to transfer this principle of choice of properties to electronic pens too. However, this has the disadvantage that the user usually has to change grip in order to be able to access the button which is to be depressed to obtain a desired property (e.g. color). A further disadvantage of this solution is that the number of buttons which it is possible to incorporate on a pen is limited.
The problem of being able to make a large number of selections using a limited number of buttons has of course been solved in other types of handheld electronic appliances, for example mobile phones, by introducing screen-based menu systems. However, the narrow and elongate shape of an electronic pen can only provide a small accessible area for a display, and hence a menu system solution is less suitable for this type of product. A menu system would in any case not represent an optimum user interface for a pen because the user has to move or turn the pen round in order to be able to view the display and access the operating buttons for the menu system.
A better way of making it possible for the user to select a property from among a large number of properties without substantially changing his grip on the pen is instead to use a property palette placed on the base, that is to say an area comprising partial areas or selection fields, the meaning of which is pre-defined in the pen. For example, a certain selection field in the palette can signify the color red, and the pen stores the subsequent input with the color red property.
The advantage of this procedure is that it resembles an intuitive method of producing graphical information, but the solution has a serious disadvantage in its lack of flexibility. When the definitions of different selection fields have been programmed into a pen, it is difficult to increase the number of properties because the pen's memory is limited. In addition, changing the definition of a certain property requires reprogramming of the pen, and, if several different palettes are to be used, extensive and regular reprogramming of the pen is required, which complicates the construction of the pen.
In a more flexible solution, instead of storing the meaning of each pen stroke in the electronic pen, all definitions and interpretations of pen strokes on palettes and also on conventional writing surfaces are handled in a remote server with which the pen can communicate. The advantage of this solution is that it is much easier to reprogram a server for interpretation of certain properties than to reprogram a large number of pens.
The solution indicated in the previous paragraph is described in more detail in WO 01/71473 which relates to an arrangement for inputting graphical information into a computer system, the graphical information arising when a drawing device is moved in relation to a base which is provided with a position-coding pattern. The drawing device is arranged to record positions on the base, and a computer system connected to the pen is arranged to interpret position information from a first area as graphical information, and position information from a second area as control information concerning a visual property,of the graphical information. Examples of such properties are line thickness and line color.
The inventors of the present invention have now realized that there is a problem with a solution according to the previous paragraph: when a user of an electronic pen with selectable properties begins a new session of producing graphical information by means of the pen, said user cannot always remember the most recently selected settings from the most recently preceding writing session. This can happen, for example, in cases where a long period of time has elapsed since the last time the electronic pen was used.
An intuitive solution to this problem would be to provide the user with feedback concerning the selected properties via a user interface on the pen. However, because of the desired configuration of an optimum electronic pen, especially given the requirement for a low weight and an elongate shape for user-friendly handling, and also given the requirement in respect of a low price, the possibilities of constructing a user interface are limited. In addition, any property settings would either need to be stored locally in some way in the pen (which is not desirable for the above reasons) or transferred to the pen from the server.
The inventors of the present invention have also realized that there is another problem associated with the fact that it is often advantageous to provide the writing support in an arrangement like a book, file or notepad, where a number of “empty” input pages of paper are supplemented with a property palette which is either printed on a separate page of paper or on a special part of the input pages. A property selection on the palette page can and will then affect all subsequent inputs on the input pages, regardless of which page this takes place on. It is necessary in this connection to transfer all pen strokes input on the palette page to the server so that the latter is able to process (render) the pen strokes on the input pages in the correct way. This procedure can therefore involve transmitting large amounts of information on pen strokes from the palette page to the server, and this in turn has disadvantages in terms of long transmission times, costs associated with these long transmission times, high power consumption in the pen, and the need for large storage capacity in the server.